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From: tip-bot for Joerg Roedel <tipbot@zytor.com>
To: linux-tip-commits@vger.kernel.org
Cc: aarcange@redhat.com, boris.ostrovsky@oracle.com,
	llong@redhat.com, dave.hansen@intel.com, namhyung@kernel.org,
	torvalds@linux-foundation.org, eduval@amazon.com, bp@alien8.de,
	dhgutteridge@sympatico.ca, gregkh@linuxfoundation.org,
	acme@kernel.org, jolsa@redhat.com, jgross@suse.com,
	tglx@linutronix.de, mingo@kernel.org,
	alexander.shishkin@linux.intel.com, dvlasenk@redhat.com,
	jroedel@suse.de, David.Laight@aculab.com, hpa@zytor.com,
	will.deacon@arm.com, jpoimboe@redhat.com, luto@kernel.org,
	brgerst@gmail.com, linux-kernel@vger.kernel.org, jkosina@suse.cz,
	pavel@ucw.cz, peterz@infradead.org
Subject: [tip:x86/pti] x86/kexec: Allocate 8k PGDs for PTI
Date: Mon, 30 Jul 2018 04:58:57 -0700	[thread overview]
Message-ID: <tip-ca38dc8f2724d101038b1205122c93a1c7f38f11@git.kernel.org> (raw)
In-Reply-To: <1532533683-5988-4-git-send-email-joro@8bytes.org>

Commit-ID:  ca38dc8f2724d101038b1205122c93a1c7f38f11
Gitweb:     https://git.kernel.org/tip/ca38dc8f2724d101038b1205122c93a1c7f38f11
Author:     Joerg Roedel <jroedel@suse.de>
AuthorDate: Wed, 25 Jul 2018 17:48:03 +0200
Committer:  Thomas Gleixner <tglx@linutronix.de>
CommitDate: Mon, 30 Jul 2018 13:53:48 +0200

x86/kexec: Allocate 8k PGDs for PTI

Fuzzing the PTI-x86-32 code with trinity showed unhandled
kernel paging request oops-messages that looked a lot like
silent data corruption.

Lot's of debugging and testing lead to the kexec-32bit code,
which is still allocating 4k PGDs when PTI is enabled. But
since it uses native_set_pud() to build the page-table, it
will unevitably call into __pti_set_user_pgtbl(), which
writes beyond the allocated 4k page.

Use PGD_ALLOCATION_ORDER to allocate PGDs in the kexec code
to fix the issue.

Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: David H. Gutteridge <dhgutteridge@sympatico.ca>
Cc: "H . Peter Anvin" <hpa@zytor.com>
Cc: linux-mm@kvack.org
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: David Laight <David.Laight@aculab.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Eduardo Valentin <eduval@amazon.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: aliguori@amazon.com
Cc: daniel.gruss@iaik.tugraz.at
Cc: hughd@google.com
Cc: keescook@google.com
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Waiman Long <llong@redhat.com>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: joro@8bytes.org
Link: https://lkml.kernel.org/r/1532533683-5988-4-git-send-email-joro@8bytes.org

---
 arch/x86/kernel/machine_kexec_32.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/machine_kexec_32.c b/arch/x86/kernel/machine_kexec_32.c
index d1ab07ec8c9a..5409c2800ab5 100644
--- a/arch/x86/kernel/machine_kexec_32.c
+++ b/arch/x86/kernel/machine_kexec_32.c
@@ -56,7 +56,7 @@ static void load_segments(void)
 
 static void machine_kexec_free_page_tables(struct kimage *image)
 {
-	free_page((unsigned long)image->arch.pgd);
+	free_pages((unsigned long)image->arch.pgd, PGD_ALLOCATION_ORDER);
 	image->arch.pgd = NULL;
 #ifdef CONFIG_X86_PAE
 	free_page((unsigned long)image->arch.pmd0);
@@ -72,7 +72,8 @@ static void machine_kexec_free_page_tables(struct kimage *image)
 
 static int machine_kexec_alloc_page_tables(struct kimage *image)
 {
-	image->arch.pgd = (pgd_t *)get_zeroed_page(GFP_KERNEL);
+	image->arch.pgd = (pgd_t *)__get_free_pages(GFP_KERNEL | __GFP_ZERO,
+						    PGD_ALLOCATION_ORDER);
 #ifdef CONFIG_X86_PAE
 	image->arch.pmd0 = (pmd_t *)get_zeroed_page(GFP_KERNEL);
 	image->arch.pmd1 = (pmd_t *)get_zeroed_page(GFP_KERNEL);

  reply	other threads:[~2018-07-30 12:00 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-07-25 15:48 [PATCH 0/3] PTI x86-32 Updates and Fixes Joerg Roedel
2018-07-25 15:48 ` [PATCH 1/3] x86/mm: Remove in_nmi() warning from vmalloc_fault() Joerg Roedel
2018-07-30 11:57   ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-25 15:48 ` [PATCH 2/3] Revert "perf/core: Make sure the ring-buffer is mapped in all page-tables" Joerg Roedel
2018-07-30 11:58   ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-25 15:48 ` [PATCH 3/3] x86/kexec: Allocate 8k PGDs for PTI Joerg Roedel
2018-07-30 11:58   ` tip-bot for Joerg Roedel [this message]
2018-07-30  7:08 ` [PATCH 0/3] PTI x86-32 Updates and Fixes David H. Gutteridge

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